The in vivo administration of chemical carcinogens, benzopyrene (BP) and 3-methycholanthrene (MC), increases the activity of extra-hepatic microsomal enzyme systems capable of metabolizing their inducers. The microsomal fraction of the adult rat kidney contains an aryl hydrocarbon hydrocarbon hydroxylase system which can be induced 5-to 30-fold by a single dose of either BP or MC; concomitant with this induced enzymatic activity is an increase in the content of cytochrome P-450K. The proposed research project will be directed toward solubilizing, purifying and reconstituting the aryl hydrocarbon hydroxylase system in an attempt to determine whether this enzyme system is related to or totally separate from the kidney microsomal mono-oxygenase system which catalyzes the omega- and omega-1-hydroxylation of fatty acids. Although the kidney aryl hydrocarbon hydroxylase system is induced by administration of polycylic hydrocarbons, the kidney omega-and omega-1-hydroxylation of fatty acids is unaffected.